Findings taken from a group of elderly adults who drank the juice every day indicated improvements in cognitive function and blood flow to the brain

Additional indications point to the activation of specific brain areas during cognitive tasks as well as a boost in working memory.

“Epidemiological studies demonstrate that risk of dementia is reduced by higher fruit and vegetable intake, and cognitive function is better in healthy older adults with a diet rich in plant-based foods,” ​said lead author Dr Joanna Bowtell, associate professor of Sport and Health Sciences at the University of Exeter.

“A group of polyphenols known as flavonoids, which are highly abundant in plants, are likely to be important bioactive components contributing to these favourable effects.”​

While blueberries are a rich source of flavonoids, the nutrient’s brain enhancing effects have already been observed in other flavonoid-packed fruits and foods.

Consumption of high flavanol cocoa improved cognitive function in healthy older adults after eight weeks in comparison to a low flavanol cocoa supplement.

Similarly, four weeks of supplementation with pomegranate, which are rich in the polyphenols from the elligitannins family, increased task-related brain activation and cognitive function in healthy older adults.

There was also evidence suggesting improvement in working memory after blueberry supplementation when compared to the placebo.

“The present study is the first to directly measure changes in cerebral perfusion in response to chronic fruit supplements, using arterial spin labelling,”​ the study commented.

“The mechanism of these effects is likely to be related to improved availability of the potent vasodilator, nitric oxide (NO), in the vasculature.”​

Improved vascular function​

Cell function has been has been shown to plays an important role in regulating cerebral blood flow through the release of vasoactive substances including NO.

The team thought it plausible that interventions which enhance vascular function could also improve cerebral perfusion and hence cognitive function.

In support of this hypothesis, one study​​ found a meaningful link between neurovascular coupling and cognitive function in elderly participants with vascular risk factors. These factors showed enhancement after 30 days of high flavanol cocoa consumption.

“Blueberry concentrate consumed once per day for 12 weeks increased activation of brain areas associated with ​cognitive processes including memory and executive function, which tend to deteriorate with age,”​ the study concluded.

“These effects of blueberry appear to be mediated by improved vascular function as suggested by the improved resting perfusion of ​gray matter in the parietal and occipital lobes of the brain.”​